A MODIFIED TUBELESS SOLAR COLLECTOR PARTIALLY FILLED WITH POROUS SUBSTRATE

In this work, the thermal performance of a conventional tubeless colle ctor is improved by inserting porous substrates at the inner side of t he collector absorber plate. The porous substrates improve the convect ive heat transfer coefficient between the absorber plate and the fluid . This improvement is investigated numerically and its effects on the efficiency and the useful gain of the collector are evaluated. It is f ound that inserting the porous substrate may raise the collector effic iency by 3-32% especially at high Values of the overall heat loss coef ficient. (C) 1998 Elsevier Science Ltd. All rights reserved.